1. Field of the Invention
The present invention relates to methods of treating keratin based substrates using novel cosmetically acceptable compositions containing a cosmetically acceptable medium that includes polymer compositions and methods for treating keratin. The cosmetically acceptable medium can be a hair or skin care product, such as a shampoo, conditioner, shower gel, bar soap, styling product, or rinse, or a skin care product, such as a cleanser, lotion, or cream.
2. Brief Description of the Prior Art
The surface properties of keratin are of interest in cosmetic science, and there has been a long-standing desire to discover ingredients, which will beneficially affect the topical and bulk condition of keratinous substrates, such as hair and skin. For example, such ingredients must have adequate adherent properties, so that they are not only adsorbed initially, but are also retained on exposure to water. This property is referred to as “substantivity,” i.e., the ability of a material to be adsorbed onto keratin and to resist removal by water rinse-off.
Hair is composed of keratin, a sulfur-containing fibrous protein. The isoelectric point of keratin, and more specifically of hair, is generally in the pH range of 3.2-4.0. Therefore, at the pH of a typical shampoo, hair carries a net negative charge. Consequently, cationic polymers have long been used as conditioners in shampoo formulations, or as a separate treatment, in order to improve the wet and dry combability of the hair. The substantivity of the cationic polymers for negatively charged hair along with film formation facilitates detangling during wet hair combing and a reduction in static flyaway during dry hair combing. Cationic polymers generally also impart softness and suppleness to hair.
When cationic polymers are added to shampoos (or to skin care products, such as cleaning compositions) containing anionic surfactants, formation of highly surface active association complexes generally takes place, which imparts improved foam stability to the shampoo. Maximum surface activity and foam stability, or lather, are achieved at near stoichiometric ratios of anionic surfactant: cationic polymer, where the complex is least water-soluble. Generally, cationic conditioners exhibit some incompatibility at these ratios. Compatibility gives a commercially more desirable clear formulation, while incompatibility leads to a haze or precipitation, which is aesthetically less desirable in some formulations.
Hair fixative properties, such as curl retention, are believed to be directly related to film-forming properties of cationic polymers, as well as to molecular weight, with performance generally increasing with increasing molecular weight. However, the fixative properties conferred by cationic polymers generally tend to have a reciprocal relationship to other conditioning properties, i.e., good curl retention usually means that properties, such as wet compatibility, will suffer, and vice versa.
Keratin conditioning additives generally are of three primary types: cationic polymers, proteins or protein derivatives, and fatty quaternary ammonium compounds. Commonly used cationic polymers include: quaternary nitrogen-containing hydroxyethyl cellulose compounds, copolymers of vinylpyrrolidone and dimethylaminoethylmethacrylate, and amino functional polydimethyl-siloxane. Hydrolyzed animal protein has been frequently used as a keratin conditioner. Also used are natural products, such as collagen and casein. Suitable quaternary ammonium compounds include such products as stearyl dimethyl ammonium chloride.
Generally, two broad areas of skin care products have been recognized as skin conditioners: emollients and humectants. Emollients generally provide improved moisture retention in the skin and plasticization/softening of the skin. Common commercial emollients are mineral oil; petrolatum; aliphatic alcohols, such as stearyl alcohol; lanolin and its derivatives; glycol stearate; and fatty acids, such as triethanolamine oleate. Humectants generally attract moisture, retard evaporation of water from the skin surface, and plasticize/soften skin. Common commercial humectants include glycerin, propylene glycol, sorbitols, and polyethylene glycols.
A desirable skin conditioner should impart at least some of the attributes of an emollient or a humectant, as well as provide improved lubricity and feel to the skin after treatment and/or reduce skin irritation caused by other components in the conditioner, such as, for example, soaps, detergents, foam boosters, surfactants, and perfumes. It is known by those skilled in the art that cationic polymers may be employed as skin and nail conditioners.
At times, it is also desirable that the ingredients of skin and nail care products have adequate adherent properties, so that they are not only adsorbed initially, but are also retained on exposure to water. This property, as in hair care applications, is referred to as “substantivity,” i.e., the ability of a material contacted with the keratin of skin or nails to resist removal by water rinse-off. Generally, pH's typical of use conditions, skin, and nails carry a net negative charge. Consequently, cationic polymers have long been used as conditioners in nail and skin care formulations. The substantivity of the cationic polymers for negatively charged skin and nails leads to film formation that facilitates lubricity, moisturizing, and feel.
The skin and nail conditioning properties of lubricity, moisturizing, and feel, are related to the film-forming properties of the cationic polymers, as well as to molecular weight, with performance generally increasing with increasing molecular weight.
Conditioning additives comprising copolymers of dimethyldiallylammonium chloride and other monomers are well known; see, e.g., European Patent No. EP 308189 to Jordan et al. (with acrylamide), European Patent No. EP 0 308 190 to Winkler et al., and U.S. Pat. No. 4,803,071 to lovine et al. (with hydroxyethyl cellulose). Amphoteric betaines have also been employed in cosmetic compositions; see Great Britain Patent No. GB 2,113,245 to Grollier et al., which discloses use of betainized dialkylaminoalkyl(meth)acrylate together with a cationic polymer.
The use of polymers of diallyldimethylammonium chloride (DADMAC) in the treatment of keratin is also known. See, e.g., U.S. Pat. Nos. 4,175,572 to Hsiung et al. and 3,986,825 to Sokol. U.S. Pat. No. 5,296,218 to Chen et al. discloses DADMAC-based ampholyte terpolymers containing acrylamide for hair care applications, while U.S. Pat. No. 5,275,809 to Chen et al. discloses DADMAC-based ampholyte terpolymers containing acrylamidomethylpropyl sulfonic acid for hair care uses.
U.S. Pat. No. 4,923,694 to Shih et al. discloses copolymers of vinyl pyrrolidone and (meth)acrylic cationic monomers that are useful for treating hair. These polymers are able to provide good hair styling properties at low concentrations of cationic monomer, but provide limited substantivity due to their relatively low cationic charge density. When the cationic charge density is increased, the polymers disclosed by Shih et al. become difficult to formulate with due to their decreasing compatibility with anionic surfactants.
U.S. Pat. No. 5,609,862 to Chen et al. discloses hair conditioning polymers comprised of acrylamide, acrylic acid, and a cationic monomer. The conditioning polymers disclosed by Chen et al. are very compatible with anionic surfactants but demonstrate poor compatibility with amphoteric and cationic surfactants. Further, the conditioning polymers of Chen et al. provide poor hair styling properties and only minor conditioning benefit to hair.
U.S. Pat. Nos. 5,879,670 and 6,066,315 to Melby et al. disclose conditioning polymers that include acrylic acid or acrylamidomethylpropanesulfonic acid monomers, (meth) acrylamidopropyl trimethyl ammonium chloride cationic monomers, and (meth)acrylate ester nonionic monomers. The conditioning polymers of Melby et al. are difficult to formulate at low pH and do not provide good hair styling properties.
U.S. Pat. No. 6,110,451 to Matz et al. discloses synergistic combinations of cationic and ampholytic polymers for cleansing and/or conditioning keratin based substrates. The compositions disclosed are often not stable, as strongly cationic polymers tend to form insoluble polymer-polymer complexes and cause the cleansing or conditioning formulation to become hazy, or the polymer-polymer complex precipitates altogether.
Interpenetrating polymer networks (IPN) are intimate combinations of two polymers. The IPN can be in network form, where at least one polymer is synthesized in the immediate presence of the other. In an IPN, at least one of the two polymers is crosslinked and the other may be a linear polymer (not crosslinked). The term IPN has been variously used to describe materials where the two polymers in the mixture are not necessarily bound together, but the components are physically associated.
U.S. Pat. No. 5,925,379 to Mandeville, III et al. discloses a method for removing bile salts from a patient where a polymer network composition, which includes a cationic polymer is administered to the patient. The polymer network composition can include an interpenetrating polymer network, where each polymer within the network is crosslinked or an interpenetrating polymer network, where at least one polymer within the network is not crosslinked. Crosslinking the polymers renders the polymers non-adsorbable and stable. The polymer network composition does not dissolve or otherwise decompose to form potentially harmful byproducts and remains substantially intact so that it can transport ions out of the body following binding of bile acids.
U.S. Pat. No. 5,693,034 to Buscemi et al. discloses an angioplasty catheter that includes a composition coating on a distal end. The coating composition includes the reaction product of vinyl monomers polymerized to form a crosslinked polymer that adheres to the surface of the device in the presence of an uncrosslinked, linear, water-soluble, hydrophilic hydrogel.
U.S. Pat. No. 5,644,049 to Giusti et al. discloses a biomaterial that includes an IPN. The IPN includes an acidic polysaccharide, such as hyaluronic acid and a non-toxic, non-carcinogenic synthetic polymer. The synthetic polymer may be crosslinked or grafted onto the acidic polysaccharide. The crosslinking or grafting is achieved using compounds capable of generating radicals or via functional groups on the acidic polysaccharide and the synthetic chemical polymer.
As the IPN examples described above illustrate, an IPN includes at least one crosslinked polymer with one or more other polymers, which may or may not be crosslinked in intimate combination with each other. When water-soluble polymers are included in the IPN, the resulting IPN is water dispersible, but it does not dissolve in water. While the use of an IPN may provide useful combinations of properties, its water insolubility can be a detriment in cosmetic compositions for treating keratin based substrates.
U.S. Pat. No. 4,028,290 to Reid discloses a complex mixture of crosslinked grafted polysaccharide and acrylamide copolymers that have increased water-absorbing and binding capacity. The copolymers are prepared by reacting a polysaccharide, such as cellulose or starch, acrylamide using a bisulfite-persulfate-ferrous ammonium sulfate grafting initiator.
U.S. Pat. No. 4,703,801 to Fry et al. discloses a graft polymer that has a backbone derived from lignin, lignite, derivatized cellulose, or synthetic polymers, such as polyvinyl alcohol, polyethylene oxide, polypropylene oxide and polyethyleneimine, and pendant grafted groups that include homopolymers and copolymers of 2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile, N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylate, and their salts. The graft copolymers are prepared by reacting the backbone polymer with ceric salts and a persulfate-besulfite redox system in the presence of the selected monomers. The graft copolymers are useful in cementing compositions for use in oil, gas, water and other well cementing operations and impart improved fluid loss capabilities.
U.S. Pat. No. 4,464,523 to Neigel et al. discloses graft copolymers of cellulose derivatives and N,N-diallyl,N-N-dialkyl ammonium chlorides or bromides, prepared using a dry or substantially solvent-free system. The preparation includes impregnating a concentrated aqueous solution of the N,N-diallyl-N,N-dialkyl ammonium halide, water-soluble surfactant, and redox catalyst onto the dry cellulose substrate, heating the reaction mass for sufficient time to achieve polymerization and then drying.
As described above, graft copolymers of polysaccharide and cellulosic backbone polymers are generally prepared by reacting portions of the backbone polymer with a redox catalyst generally including a ceric or ferrous salt to generate one or more free radicals. The free radicals on the backbone polymer then react with the monomers that are present to literally grow in graft polymer from the backbone polymer.
Graft copolymers differ from IPN's in that a first polymer acts as a substrate onto which another polymer is added, or a site on the first polymer is involved in initiating polymerization to form a pendant polymer arm. Graft copolymers can readily be formed from polysaccharide or cellulosic backbones using methods well known in the art. Examples of such methods include the ceric salt redox method (U.S. Pat. No. 3,770,673 to Slagl et al.) and graft initiation using formaldehyde and sodium metabisulfite (U.S. Pat. No. 4,105,605 to Cottrell et al.). In order to achieve a high degree of grafting, heavy metal ions, such as cerium IV or ferrous, or reagents, such as formaldehyde, are used to augment the grafting reaction. In cases where a composition containing the graft copolymer is to be used on human skin and hair, the presence of heavy metal ions or formaldehyde is undesirable because they are considered by many to be cancer causing agents in humans, as well as environmentally harmful.
Further, graft copolymers are limited in the functional properties that they can provide. For example, the graft copolymer of U.S. Pat. No. 4,464,523 Neigel et al. has highly charged cationic arms and a neutral backbone. The possible polymer confirmations that allow such a polymer to interact with a keratin substrate are limited compared to a linear polymer. Further, the localized high charge density of the cationic arms can lead to incompatibility with many anionic surfactants, making it difficult to formulate with. These limitations result in inferior performance when such a polymer is used in keratin treating and/or cleansing compositions. For example, such polymers do not provide adequate wet combing properties when used in hair care formulations. Further the high localized change density in cationic graft copolymers of the leads to the polymer building up on the hair causing an undesirable property of the hair to not hold its shape especially after styling.
There remains a need for a polymeric conditioning additives for keratin based substrates that is easy to formulate with (easy to make clear surfactant based formulations), does not change over time, and provides excellent hair styling properties as well as excellent conditioning properties to hair, skin, and nails.